Method for controlling uplink transmission power and wireless device using same

ABSTRACT

A method for uplink transmission in a wireless communication system, and a user equipment (UE) therefore are discussed. The method according to an embodiment includes determining a transmission power of a first uplink signal; determining a transmission power of a second uplink signal; preparing to transmit the first uplink signal toward a first cell belonging to a first timing advance group (TAG); preparing to transmit the second uplink signal toward a second cell belonging to a second TAG; and if the first uplink signal toward the first cell belonging to the first TAG at an n th  subframe and the second uplink signal of the second cell belonging to the second TAG at an (n+1) th  subframe are overlapped, determining whether to adjust a total transmission power or drop the first uplink signal at the n th  subframe.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Continuation of copending U.S. application Ser.No. 14/112,482, filed on Oct. 17, 2013, which is the National Phase ofPCT/KR2012/007930, filed on Sep. 28, 2012, which claims the benefit ofpriority under 35 U.S.C. 119(e) to U.S. Provisional Application No.61/541,044, filed on Sep. 29, 2011, 61/554,493, filed on Nov. 1, 2011,61/591,279, filed on Jan. 27, 2012, 61/611,590, filed on Mar. 16, 2012,61/613,467, filed on Mar. 20, 2012, 61/644,439, filed on May 9, 2012,61/645,566, filed on May 10, 2012, 61/667,935, filed on Jul. 3, 2012,61/678,120, filed on Aug. 1, 2012 and 61/681,636, filed on Aug. 10,2012, the entire contents of which are hereby incorporated by referencein their entirety.

BACKGROUND OF THE INVENTION

The present invention relates to wireless communications, and moreparticularly, to a method for controlling an uplink transmit power in awireless communication system, and a wireless device using the method.

3rd generation partnership project (3GPP) long term evolution (LTE) isan improved version of a universal mobile telecommunication system(UMTS) and is introduced as the 3GPP release 8. The 3GPP LTE usesorthogonal frequency division multiple access (OFDMA) in a downlink, anduses single carrier-frequency division multiple access (SC-FDMA) in anuplink. The 3GPP LTE employs multiple input multiple output (MIMO)having up to four antennas. In recent years, there is an ongoingdiscussion on 3GPP LTE-advanced (LTE-A) that is an evolution of the 3GPPLTE.

As disclosed in 3GPP TS 36.211 V8.7.0 (2009-05) “Evolved UniversalTerrestrial Radio Access (E-UTRA); Physical Channels and Modulation(Release 8)”, a physical channel of the LTE can be classified into adownlink channel, i.e., a physical downlink shared channel (PDSCH) and aphysical downlink control channel (PDCCH), and an uplink channel, i.e.,a physical uplink shared channel (PUSCH) and a physical uplink controlchannel (PUCCH).

To decrease an interference caused by uplink transmission between userequipments (UEs), it is important for a base station (BS) to maintainuplink time alignment of the UEs. The UE may be located in any area in acell. An uplink signal transmitted by the UE may arrive to the BS at adifferent time according to the location of the UE. A signal arrivaltime of a UE located in a cell edge is longer than a signal arrival timeof a UE located in a cell center. On the contrary, the signal arrivaltime of the UE located in the cell center is shorter than the signalarrival time of the UE located in the cell edge.

To decrease the interference between the UEs, the BS needs to performscheduling so that uplink signals transmitted by the UEs in the cell canbe received every time within a boundary. The BS has to properly adjusttransmission timing of each UE according to a situation of each UE. Suchan adjustment is called an uplink time alignment. A random accessprocess is one of processes for maintaining the uplink time alignment.The UE acquires a time alignment value (or also referred to as a timingadvance (TA)) through the random access process, and maintains theuplink time alignment by applying the time alignment value.

In addition, a transmit power of the UE needs to be adjusted to mitigatean interference caused by uplink transmission. It is difficult for theBS to receive uplink data if the transmit power of the UE is too low. Ifthe transmit power of the UE is too high, uplink transmission may causea significant interference to transmission of another UE.

Recently, multiple serving cells are introduced to provide a higher datarate. However, the same time alignment value has been applied to allserving cells under the assumption that serving cells have adjacentfrequencies or have similar propagation properties.

There is a need for a method capable of adjusting an uplink transmitpower between a plurality of serving cells when configuring theplurality of serving cells to which different time alignment values areapplied.

SUMMARY OF THE INVENTION

The present invention provides a method of controlling an uplinktransmit power among a plurality of timing advance (TA) groups, and awireless device using the method.

In one aspect, there is provided a method of controlling an uplinktransmit power in a wireless communication system. The method maycomprise determining a first transmit power of a first uplink channel tobe transmitted using a first radio resource to a first serving cell anddetermining a second transmit power of a second uplink channel to betransmitted using a second radio resource to a second serving cell. Thefirst serving cell belongs to a first timing advance (TA) group, and thesecond serving cell belongs to a second TA group different from thefirst TA group. The first radio resource and the second radio resourceentirely or partially overlap. A sum of the first and second transmitpowers in the overlapping portion is determined not to exceed a maximumtransmit power.

The first and second radio resources may be at least one subframeincluding a plurality of orthogonal frequency division multiplexing(OFDM) symbols.

At least any one of the first and second transmit powers may be adjustedbased on a subframe boundary.

The first and second uplink channels may include at least any one of aphysical uplink shared channel (PUSCH), a physical uplink controlchannel (PUCCH), a physical random access channel (PRACH), and asounding reference signal (SRS).

In other aspect, there is provided a wireless device for controlling anuplink transmit power in a wireless communication system. The wirelessdevice may comprise a radio frequency (RF) unit for transmitting andreceiving a radio signal; and a processor operatively coupled to the RFunit. The processor may be configured for: determining a first transmitpower of a first uplink channel to be transmitted using a first radioresource to a first serving cell and determining a second transmit powerof a second uplink channel to be transmitted using a second radioresource to a second serving cell. The first serving cell belongs to afirst timing advance (TA) group, and the second serving cell belongs toa second TA group different from the first TA group. The first radioresource and the second radio resource entirely or partially overlap. Asum of the first and second transmit powers in the overlapping portionis determined not to exceed a maximum transmit power.

When a plurality of timing advance (TA) groups are configured, an uplinktransmit power can be adjusted among cells belonging to different TAgroups.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a downlink radio frame structure in 3rd generationpartnership project (3GPP) long term evolution (LTE).

FIG. 2 is a flowchart showing a random access procedure in 3GPP LTE.

FIG. 3 shows an example of a random access response.

FIG. 4 shows an example of multiple carriers.

FIG. 5 shows an uplink (UL) propagation difference among multiple cells.

FIG. 6 shows an example in which a timing advance (TA) varies amongmultiple cells.

FIG. 7 shows a method of controlling a transmit power according to anembodiment of the present invention.

FIG. 8 shows a method of controlling a transmit power according toanother embodiment of the present invention.

FIG. 9 shows a method of controlling a transmit power according toanother embodiment of the present invention.

FIG. 10 shows a method of controlling a transmit power according toanother embodiment of the present invention.

FIG. 11 shows an example of TA adjustment for a TA group.

FIG. 12 shows overlapping caused by transmission timing adjustment.

FIG. 13 shows UL transmission according to an embodiment of the presentinvention.

FIG. 14 is a block diagram showing a wireless communication systemaccording to an embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

A wireless device may be fixed or may have mobility, and may be referredto as another term such as a User Equipment (UE), a mobile station (MS),a user terminal (UT), a subscriber station (SS), or a mobile terminal(MT). In general, the base station may refer to a fixed stationcommunicating with a wireless device, and also may be referred to asanother term such as an evolved-NodeB (eNB), a Base Transceiver System(BTS), or an Access Point.

Hereinafter, it will be described that the present invention is appliedbased on 3rd Generation Partnership Project (3GPP) long term evolution(LTE) or 3GPP LTE-Advanced (LTE-A). This is for exemplary purposes, andthe present invention may be applicable to various wirelesscommunication systems. Hereinafter, LTE includes the LTE and/or theLTE-A.

FIG. 1 illustrates a structure of a downlink radio frame in the 3GPPLTE. This may refer to paragraph 6 of 3GPP TS 36.211 V8.7.0 (2009-05)“Evolved Universal Terrestrial Radio Access (E-UTRA); Physical Channelsand Modulation (Release 8)”.

A radio frame includes 10 subframes numbered with indices 0 to 9. Onesubframe includes two consecutive slots. The time required to transmitone subframe is called a transmission time interval (TTI). For example,the length of one subframe may be 1 ms and the length of slot may be 0.5ms.

One slot may include a plurality of orthogonal frequency divisionmultiplexing (OFDM) symbols in a time zone. Since the 3GPP LTE usesorthogonal frequency division multiple access (OFDMA) in a downlink(DL), the OFDM symbol is only to express one symbol period in a timezone and thus does not limit a multiple access scheme or name. Forexample, the OFDM symbol may be called different names such as a singlecarrier-frequency division multiple access (SC-FDMA) symbol and a symbolperiod.

Although it is exemplarily described that one slot includes 7 OFDMsymbols, the number of OFDM symbols in one slot may vary depending onthe length of a Cyclic Prefix (CP). According to 3GPP TS 36.211 V8.7.0,one slot in a regular CP includes seven OFDM symbols and one slot in anextended CP includes six OFDM symbols.

A resource block (RB) is a resource allocation unit and includes aplurality of subcarriers in one slot. For example, if one slot includesseven OFDM symbols in a time zone and a RB includes twelve subcarriersin a frequency domain, one RB may include 7×12 resource elements (REs).

A DL subframe is divided into a control region and a data region in atime zone. The control region includes up to three OFDM symbols in thefront of a first slot in a subframe, but the number of OFDM symbols inthe control region may vary. A Physical Downlink Control Channel (PDCCH)and another control channel are allocated to the control region and aPDSCH is allocated to the data region.

As disclosed in 3GPP TS 36.211 V8.7.0, a physical channel in the 3GPPLTE may be divided into a data channel (i.e. a Physical Downlink SharedChannel (PDSCH) and a Physical Uplink Shared Channel (PUSCH)) and acontrol channel (i.e. a Physical Downlink Control Channel (PDCCH), aPhysical Control Format Indicator Channel (PCFICH), a PhysicalHybrid-ARQ Indicator Channel (PHICH), and a Physical Uplink ControlChannel (PUCCH)).

The PCFICH transmitted from the first OFDM symbol of a subframe carriesa control format indicator (CFI) for the number of OFDM symbols (i.e.the size of a control region) used for the transmission of controlchannels in the subframe. A terminal receives the CFI first on thePCFICH and then monitors the PDCCH.

Unlike the PDCCH, the PCFICH does not use blind decoding and istransmitted through the fixed PCFICH resource of a subframe.

The PHICH carries a positive-acknowledgement(ACK)/negative-acknowledgement (NACK) signal for a hybrid automaticrepeat request (HARD). The ACK/NACK signal for uplink (UL) data on thePUSCH, which is transmitted by a terminal, is transmitted on the PHICH.

A Physical Broadcast Channel (PBCH) is transmitted from the front fourOFDM symbols of the second slot in the first subframe of a radio frame.The PBCH carries system information essential when a terminalcommunicates with a base station, and the system information transmittedthrough the PBCH is called a master information block (MIB). Compared tothis, the system information, which is transmitted on the PDSCHindicated by the PDCCH, is called a system information block (SIB).

The control information transmitted through the PDCCH is called asdownlink control information (DCI). The DCI may include the resourceallocation of a PDSCH (also, referred to as DL grant), the resourceallocation of a PUSCH (also, referred to as UL grant), a set of transmitpower control commands on each UE in an arbitrary UE group, and/or theactivation of a Voice over Internet Protocol (VoIP).

The 3GPP LTE uses blind decoding to detect a PDCCH. The blind decodingdemasks a desired identifier on CRC of a received PDCCH (also, referredto as a candidate PDCCH), and checks CRC errors in order to confirmwhether a corresponding PDCCH is its control channel.

A base station determines a PDCCH format according to DCI to betransmitted to a terminal, attaches Cyclic Redundancy Check (CRC) to theDCI, and then, masks a unique identifier (also, referred to as a RadioNetwork Temporary Identifier (RNTI)) on the CRC according to the owneror purpose of a PDCCH.

The control region in a subframe includes a plurality of control channelelement (CCEs). The CCE is a logical allocation unit used to provide anencoding rate according to a state of a radio channel to a PDCCH andcorresponds to a plurality of resource element groups (REGs). The REGincludes a plurality of resource elements. According to a linkagebetween the number of CCEs and an encoding rate provided by the CCEs,the format of a PDCCH and the number of available bits in the PDCCH aredetermined.

One REG includes four REs and one CCE includes nine REGs. In order toconfigure one PDCCH, {1, 2, 4, and 8} CCEs may be used and an element ofeach of {1, 2, 4, and 8} CCEs is referred to as a CCE aggregation level.

A base station determines the number of CCEs used for the transmissionof a PDDCH according to a channel state. For example, one CCE may beused for PDCCH transmission to a terminal having a good DL channelstate. Eight CCEs may be used for PDCCH transmission to a terminalhaving a poor DL channel state.

A control channel configured with one or more CCE performs interleavingby a REG unit, and after a cell identifier (ID) based cyclic shift isperformed, is mapped into a physical resource.

According to 3GPP TS 36.211 V8.7.0, a DL channel includes a PUSCH, aPUCCH, a Sounding Reference Signal (SRS), and a Physical Random AccessChannel (PRACH).

The PUCCH supports a multi-format. According to a modulation schemedepending on the PUCCH format, a PUCCH having the different number ofbits per subframe may be used. A PUCCH format 1 is used for thetransmission of a Scheduling Request (SR), a PUCCH format 1a/ab is usedfor the transmission of an ACK/NACK signal for a HARQ, a PUCCH format 2is used for the transmission of a CQI, and a PUCCH format 2a/2b is usedfor the simultaneous transmission of CQI and an ACK/NACK signal. Whenonly the ACK/NACK signal is transmitted in a subframe, the PUCCH format1a/1b is used, and when the SR is transmitted alone, the PUCCH format 1is used. When the SR and ACK/NACK are simultaneously transmitted, thePUCCH format 1 is used, and an ACK/NACK signal is modulated andtransmitted in a resource allocated to the SR.

Hereinafter, maintaining UL time alignment in the 3GPP LTE will bedescribed.

In order to reduce the interference caused by UL transmission betweenterminals, it is important for a base station to maintain UL timealignment of a terminal A terminal may be located in an arbitrary areawithin a cell, and the reaching time that an uplink signal that aterminal transmits takes time to reach a base station may vary dependingon the position of each terminal. The reaching time of a terminallocated at a cell edge is longer than that of a terminal located at themiddle of a cell. On the contrary, the reaching time of a terminallocated at the middle of a cell is shorter than that located at a celledge.

In order to reduce the interference between terminals, it is necessaryfor a base station to arrange a schedule to allow UL signals thatterminals in a cell transmit to be received within each time boundary. Abase station is required to appropriately adjust the transmission timingof each terminal depending on the situation thereof, and this adjustmentis called time alignment maintenance.

One method of managing time alignment includes a random access process.A terminal transmits a random access preamble to a base station. Thebase station calculates a time alignment value for fast or slowtransmission timing of the terminal on the basis of the received randomaccess preamble. Then, the base station transmits a random accessresponse including the calculated alignment value to the terminal. Theterminal updates the transmission timing by using the time alignmentvalue.

As another method, a base station receives an SRS periodically orarbitrarily from a terminal, calculates a time alignment value of theterminal through the SRS, and then, notifies it to the terminal througha MAC control element (CE).

The time alignment value is information transmitted from a base stationto a terminal in order to maintain UL time alignment, and a TimingAlignment Command indicates the information.

In general, since a terminal has mobility, the transmission timing ofthe terminal may vary according to the moving speed and position of theterminal. Accordingly, the time alignment value that the terminalreceives may be effective for a specific time. For this, a TimeAlignment Timer is used.

After receiving a time alignment value from a base station and thenupdating time alignment, a terminal starts or restarts a time alignmenttimer. Only when the time alignment timer operates, UL transmission isavailable in the terminal. A value of the time alignment timer may benotified from a base station to a terminal through system information oran RRC message such as a Radio Bearer Reconfiguration message.

When the time alignment timer expires or does not operate, under theassumption that a base station is out of time alignment, a terminal doesnot transmit any UL signal except for a random access preamble.

FIG. 2 is a flowchart illustrating a random access process in 3GPP LTE.The random access process is used for a terminal to obtain UL alignmentwith a base station or to receive a UL radios resource allocated.

A terminal receives a root index and a physical random access channel(PRACH) configuration index from a base station. Each includes 64candidate random access preambles defined by a Zadoff-Chu (ZC) sequence,and the root index is a logical index for a terminal to generate the 64candidate random access preambles.

The transmission of a random access preamble is limited to a specifictime and a frequency resource in each cell. The PRACH configurationindex indicates a specific subframe and a preamble format available forthe transmission of a random access preamble.

Table 1 below is one example of a random access configuration disclosedin paragraph 5.7 of 3GPP TS 36.211 V8.7.0 (2009-05).

TABLE 1 PRACH configuration Preamble System frame Subframe index formatnumber number 0 0 Even 1 1 0 Even 4 2 0 Even 7 3 0 Any 1 4 0 Any 4 5 0Any 7 6 0 Any 1, 6

A terminal transmits an arbitrarily-selected random access preamble to abase station in operation S110. The terminal selects one of 64 candidaterandom access preambles. Then, the terminal selects a subframecorresponding to a PRACH configuration index. The terminal transmits theselected random access preamble in the selected subframe.

The base station receiving the random access preamble transmits a randomaccess response (PAR) to the terminal in operation S120. The randomaccess response is detected in two steps. First, the terminal detects aPDCCH masked with random access (RA)-RNTI. The terminal receives arandom access response in a Medium Access Control (MAC) Protocol DataUnit (PDU) on a PDSCH indicated by the detected PDCCH.

FIG. 3 is a view of a random access response.

The random access response may include TAC, UL grant, and temporaryC-RNTI.

The TAC is information indicating a time alignment value transmittedfrom a base station to a terminal in order to maintain UL timealignment. The terminal updates the UL transmission timing by using thetime alignment value. Once updating the time alignment, the terminalstarts or restarts a Time Alignment Timer.

The UL grant includes UL resource allocation and a transmit powercommand (TPC), which are used for the transmission of a schedulingmessage that will be described later. The TPC is used for determiningtransmit power for a scheduled PUSCH.

Referring to FIG. 2 again, the terminal transmits a message, which isscheduled according to the UL grant in the random access response, tothe base station in operation 5130.

Hereinafter, a random access preamble may be referred to as a messageM1, a random access response may be referred to as a message M2, and ascheduled message may be referred to as a message M3.

From now on, referring to paragraph 5 of 3GPP TS 36.213 V8.7.0(2009-05), UL transmit power in 3GPP LTE will be described.

A transmit power PPUSCH(i) for PUSCH transmission in a subframe i isdefined as follows.

P _(PUSCH)(i)=min{P _(CMAX),10 log₁₀(M _(PUSCH)(i))+P _(O) _(_)_(PUSCH)(j)+α(j)PL+Δ _(TF)(i)+f(i)}  Equation 1

where PCMAX is configured terminal transmit power and MPUSCH(i) is abandwidth of PUSCH resource allocation of an RB unit. PO_PUSCH(j) is aparameter consisting of the sum of a cell specific factor given in anupper layer PO_NOMINAL_PUSCH(j) and a terminal specific factorPO_UE_PUSCH(j) when j=0 and 1. α(j) is a parameter given in an upperlayer. PL is path loss estimation calculated by a terminal. ΔTF(i) is aterminal specific parameter. f(i) is a terminal specific value obtainedfrom TPC. min{A,B} is a function for outputting a smaller value of A andB.

A transmit power PPUCCH(i) for PUCCH transmission in a subframe i isdefined as follows.

P _(PUCCH)(i)=min{P _(CMAX) ,P ₀ _(_) _(PUCCH) +PL+h(n _(CQI) ,n_(HARQ))+Δ_(F) _(_) _(PUCCH)(f)+g(i)}  Equation 2

where PCMAX and PL are the same as those in Equation 1. PO_PUCCH(j) is aparameter consisting of the sum of a cell specific factor given in anupper layer PO_NOMINAL_PUCCH(j) and a terminal specific factorPO_UE_PUCCH(j). h(nCQI, nHARQ) is a value dependent on a PUCCH format.ΔF_PUCCH(F) is a parameter given by an upper layer. g(i) is a terminalspecific value obtained from TPC.

A transmit power PSRS(i) for SRS transmission in a subframe i is definedas follows.

P _(SRS)(i)=min{P _(CMAX) ,P _(SRS) _(_) _(OFFSET)+10 log₁₀(M _(SRS))+P_(O) _(_) _(PUSCH)(j)+α(j)PL+f(i)}  Equation 3

where PCMAX, PO_PUSCH(j), a(j), PL and f(i) are the same as those inEquation 1. PSRS_OFFSET represents a terminal specific parameter givenin an upper layer, and MSRS represents a bandwidth for SRS transmission.

PH(i) in a subframe I is defined as follows.

PH(i)=P _(CMAX)−{10 log₁₀(M _(PUSCH)(i))+P _(O) _(_)_(PUSCH)(j)+α(j)PL+Δ _(TF)(i)+f(i)}  Equation 4

Hereinafter, a multiple carrier system will be described.

A 3GPP LTE system supports the case that a DL bandwidth and a ULbandwidth are configured differently, but this requires one componentcarrier (CC). The 3GPP LTE system supports up to 20 MHz, and supportsonly one CC to each of UL and DL when a UL bandwidth and a DL bandwidthare different.

Spectrum aggregation (or, referred to as bandwidth aggregation andcarrier aggregation) supports a plurality of CCs. For example, if fiveCCs are allocated as granularity of a carrier unit having a 20 MHzbandwidth, the 3GPP LTE system may support the maximum bandwidth of 100MHz.

One DL CC or a pair of a UL CC and a DL CC may correspond to one cell.Accordingly, a terminal communicating with a base station through aplurality of DL CCs may receive service from a plurality of servingcells.

FIG. 4 illustrates an example of a multiple carrier.

There are three DL CCs and three UL CCs, but their numbers are notlimited thereto. In each DL CC, a PDCCH and a PDSCH are separatelytransmitted, and in each UL CC, a PUCCH and a PUSCH are separatelytransmitted. Since three pairs of DL CCs-UL CCs are defined, a terminalmay receive service from three serving cells.

A terminal may monitor a PDCCH in a plurality of DL CCs, andsimultaneously may receive a DL transmission block through a pluralityof DL CCs. A terminal may transmit a plurality of UL transmission blockssimultaneously through a plurality of UL CCs.

It is assumed that a pair of DL CC #1 and UL CC #1 becomes a firstserving cell, a pair of DL CC #2 and UL CC #2 becomes a second cell, anda DL CC #3 becomes a third serving cell. Each serving cell may beidentified through a Cell index (CI). The CI may be unique in a cell orUE-specific. Here, the example that CI=0, 1, 2 are assigned to the firstto third serving cells is shown in FIG. 4.

The serving cell may be divided into a primary cell (PCell) and asecondary cell (SCell). The primary cell operates in a primaryfrequency, and is a cell designated as a primary cell when a terminalperforms an initial connection establishing process or starts aconnection re-establishing process, or performs a hand-over process. Theprimary cell is also called a reference cell. The secondary cell mayoperate in a secondary frequency, may be configured after RRC connectionis established, and may be used for providing an additional radioresource. At least one primary cell is always configured, and asecondary cell may be added/edited/released by an upper layer signaling(for example, an RRC message).

The CI of a primary cell may be fixed. For example, the lowest CI may bedesignated as the CI of a primary cell. Hereinafter, the CI of a primarycell is 0 and the CI of a secondary cell is sequentially allocated from1.

A terminal may monitor a PDCCH through a plurality of serving cells.However, even when there are N number of serving cells, a base stationmay be configured to monitor a PDCCH for the M (M≦N) number of servingcells. Additionally, a base station may be configured to first monitor aPDCCH for the L (L≦M≦N) number of serving cells.

Even if a terminal supports a plurality of serving cells in an existing3GPP LTE, one Timing Alignment (TA) value may be commonly applied to aplurality of serving cells. However, a plurality of serving cells aregreatly far from a frequency domain, so that their propagationcharacteristics may vary. For example, in order to expand coverage orremove coverage hole, a Remote Radio Header (RRH) and devices may existin an area of a base station.

FIG. 5 illustrates a UL propagation difference between a plurality ofcells.

A terminal receives service through a primary cell and a secondary cell.The primary cell provides service by a base station and the secondarycell provides service by an RRH connected to a base station. Thepropagation delay characteristics of the primary cell and the secondarycells may vary due to the reasons such as the distance between a basestation and an RRH and a processing time of an RRH.

In this case, when the same TA value is applied to the primary cell andthe secondary cell, it may have a significant impact on the alignment ofa UL signal.

FIG. 6 illustrates an example of when a TA between a plurality of cellsis changed.

An actual TA of a primary cell is ‘TA 1’ and an actual TA of a secondarycell is ‘TA 2’. Accordingly, it is necessary that a separate TA shouldbe applied to each serving cell.

In order to apply a separate TA, a TA group is defined. The TA groupincludes one or more cells to which the same TA is applied. TA isapplied by each TA group, and a time alignment timer operates by each TAgroup.

Hereinafter, in consideration of two serving cells (i.e. a first servingcell and a second serving cell), a first serving cell belongs to a firstTA group and a second serving cell belongs to a second TA group. Thenumbers of serving cells and TA groups are for exemplary purposes only.The first serving cell may be a primary or secondary cell, and thesecond serving cell may be a primary or secondary cell.

A TA group may include at least one serving cell. A base station maynotify Information on a configuration of a TA group to a terminal.

If it is assumed that each TA group operates an independent power amp, aUL maximum transmit power of a UE may be limited for each TA group.Therefore, according to an embodiment of the present invention, aconfigured maximum transmit power PCMAX may be defined for each TAgroup. PCMAX,T is a maximum transmit power configured to a TA group T,and cells belonging to the TA group T may use PCMAX,T instead of PCMAXto obtain a transmit power and a power headroom (PH) of Equations 1 to4.

The value PCMAX,T may be determined according to a power class of a UEand a structure of a power amp, or may be given for each TA group by aBS to the UE by using an RRC message or the like. The BS may transmit tothe UE a parameter, which is used by the UE to determine PCMAX,T, byusing an RRC message, a MAC message, etc.

For each TA group, the UE may transmit information regarding a maximumtransmit power PCMAX,c of a cell c belonging to each TA group to the BSby using a MAC message, an RRC message, a PUSCH, etc. The informationmay be transmitted in the cell c.

The UE may report a power headroom (PH) for each TA group. The PH may beobtained by applying Equation 4 described above on the basis of PCMAX,T.The UE may transmit information regarding a difference between PCMAX,Tand a current transmit power of all cells belonging to the TA group tothe BS by using a MAC message, an RRC message, etc. The PH may betransmitted as a value for one TA group through one PUSCH, or may betransmitted as a value for all TA groups through one PUSCH. When thevalue for one TA group is transmitted through one PUSCH, the PUSCH maybe transmitted in a cell belonging to the TA group.

It is assumed a case where the UE reports the PH by considering all TAgroups, and subframe timing is misaligned among a plurality of TAgroups. In a subframe n, the UE can report the PH by consideringtransmission in the subframe n of each TA group. For example, whentransmission in a subframe n of a first TA group overlaps withtransmission in a subframe n+1 or a subframe n−1 of a second TA group,the PH may be calculated and reported by considering only transmissionin a subframe n of all TA groups.

If UL transmission in a subframe n of a TA group overlaps with ULtransmission or a different TA group, the PH may be obtained byconsidering the UL transmission of the different TA group in anoverlapping portion, and a greatest PH or a smallest PH or a PH in theoverlapping portion may be reported to the BS.

Now, a method of controlling a UL transmit power for each TA group willbe described.

Hereinafter, it is assumed that there are two TA groups of which a totaltransmit power sum is defined to Pmax. However, this is for exemplarypurposes only. A first serving cell belongs to a first TA group, and asecond serving cell belongs to a second TA group.

C1,n denotes a UL signal transmitted in a subframe n of the firstserving cell. C1,n+1 denotes a UL signal transmitted in a subframe n+1of the first serving cell. C2,m denotes a UL signal transmitted in asubframe m of the second serving cell. C2,m+1 denotes a UL signaltransmitted in a subframe m+1 of the second serving cell. The subframesn and m may have the same subframe number or may have different subframenumbers. The UL signal may include at least one of a PRACH, a PUCH, aPUSCH, and an SRS. Hereinafter, P1 denotes a transmit power to beapplied to transmission of C2,m, and P100 denotes a transmit power to beapplied to transmission of C1,n+1.

Since an independent TA is applied for each TA group, if a boundary of atransmission time unit (e.g., a subframe) of cells belonging todifferent TA groups is misaligned, a problem may arise in a transmitpower control of the UE.

Hereinafter, it is proposed a method of controlling a transmit power toprevent the total transmit power of the UE from exceeding Pmax.

When the UE simultaneously transmits a plurality of UL signals (or ULchannels) in different TA groups, it is proposed a power limitation rulefor reducing the total transmit power to be less than or equal to Pmaxif the total transmit power exceeds Pmax. The power limitation rule maybe applied according to a priority for each UL channel. For example, thepriority may be given in the order of a PUCCH, a PUSCH having UCI, and aPUSCH, and power reduction may be achieved starting from a channelhaving a low priority. Alternatively, power reduction may be achieved inthe same ratio between the same UL channels (i.e., between PUSCHs orbetween SRSs). Transmission of a specific UL channel may be dropped ordiscarded.

FIG. 7 shows a method of controlling a transmit power according to anembodiment of the present invention.

When a UE transmits UL signals transmitted in first and second servingcells without having to apply the total power limitation Pmax, it can beexpressed by (A) of FIG. 7. A change in the transmit power issignificant at a subframe boundary of each cell.

FIG. 7 in (B) shows that a transmit power of each UL signal is adjustedby applying a power limitation rule so that the power does not exceedsPmax in a unit of each subframe boundary.

In a duration in which a signal C2,m to be transmitted with a transmitpower P1 overlaps with C1,n, the transmit power is adjusted to atransmit power P2 by applying the power limitation rule to C1,n andC2,m. In a duration of overlapping with C1,n+1, the transmit power isadjusted to a transmit power P3 by applying the power limitation rule toC1,n+1 and C2,m.

If transmission of the UL signal to the first serving cell overlapspartially or entirely with transmission of the UL signal to the secondserving cell, the total transmit power in the overlapping portion may beadjusted not to exceed Pmax.

FIG. 8 shows a method of controlling a transmit power according toanother embodiment of the present invention.

A UE adjusts a transmit power by applying a power limitation rule for ULsignals which overlap in a start portion of the UL signal, andthereafter maintains the transmit power without alternation. A ULsignal(s) which overlaps only in an end portion of the UL signal issubjected to power adjustment within the remaining transmit powerobtained by subtracting a transmit power of the UL signal from Pmax.

When transmission of the UL signal starts in a first serving cell, if atransmission start portion does not overlap with a signal of whichtransmission starts previously in a second serving cell, the transmitpower of the UL signal to the first serving cell may be determined byconsidering another UL signal.

FIG. 8 in (A) shows a case before adjusting a transmit power.

In (B) of FIG. 8, a transmit power of C2,m is determined to P2 byapplying the power limitation rule together with C1,n which overlaps ina start portion of C2,m.

In the following figure, a blank box implies a power to be transmittedwhen each signal does not consider power limitation, and a hatched boximplies a reduced transmit power.

In (C) of FIG. 8, a transmit power of C1,n+1 is determined within theremaining power obtained by subtracting the transmit power P2 of C2,mfrom Pmax.

In (D) of FIG. 8, a transmit power of C2,m+1 is determined within theremaining power obtained by subtracting the determined transmit powerP101 from C1,n+1.

When a transmit power to a specific cell is determined in a specificsubframe, it may be determined not to exceed a power subtracted fromPmax in consideration of a transmit power of a UL signal which overlapsby being transmitted in a previous subframe of another cell. As shown inFIG. 8(B), when a maximum power of C1,n+1 is determined after a transmitpower of C1,n and C2,m is determined, a maximum power that can beallocated to C1,n+1 is a power obtained by subtracting a transmit powerof a signal subsequent to a previous subframe from Pmax, that is, apower obtained by subtracting a transmit power P2 of C2,m from Pmax. Ifthe transmit power of C1,n+1 is greater than a maximum transmit power asa result of applying a power limitation rule for C2,m+1 and C1,n+1,power adjustment can be achieved again not to exceed the maximumtransmit power.

FIG. 9 shows a method of controlling a transmit power according toanother embodiment of the present invention.

It is proposed herein that the transmit power is adjusted in the orderof duration in which UL signals of two cells overlap.

If the UL signals transmitted to two cells overlap, a transmit power ofa first transmitted UL signal is adjusted by applying a power limitationrule according to an overlapping duration. This method can be appliedrecursively for consecutive subframes.

FIG. 9 in (A) shows a case before adjusting a transmit power. Since C1,nand C2,m overlap and C1,n is first transmitted, a transmit power of C1,nis determined by applying the power limitation rule to C1,n and C2,n.

In FIG. 9 in (B), a transmit power of C2,m is adjusted from P1 to P2

In FIG. 9 in (C) and (D), since an end portion of C2,m overlaps with astart portion of C1,n+1, a transmit power of C2,m is adjusted to P3 byapplying the power limitation rule to the two signals, and a transmitpower of C1,n+1 is adjusted to P102.

In FIG. 9 in (E), the transmit power of C1,n+1, which is adjusted toP102, is finally determined to P103 by considering a portion overlappingwith C2,m+1.

As a modification of the method above, when a UL signal transmitted to afirst serving cell overlaps with two signals transmitted to a secondserving cell, a smaller transmit power may be selected between transmitpowers obtained by applying a power limitation rule to each of the firstand second UL signals.

For example, in (A) of FIG. 9, C2,m overlaps with C1,n and C2,n+2 inconsecutive time durations. In this case, as shown in (B) of FIG. 9, atransmit power is adjusted to P2 when it is adjusted together with C1,n,and is adjusted to P3 when it is adjusted together with C1,n+1. IfP3<P2, a transmit power of C2,m is P3. This process may also be repeatedfor C1,n+1. That is, C1,n+1 is transmitted with a transmit power P103which is a smaller power between a transmit power adjusted with C2,m anda transmit power adjusted with C2,m+1. In this case, a transmit power ofC1,n+1 adjusted with C2,m+1 may be determined based on a transmit powerwhich has already been adjusted one time with C2,n or based on anoriginal transmit power before being adjusted with C2,n.

The power adjustment of two cells may always start with the samesubframe number, i.e., m=n.

FIG. 10 shows a method of controlling a transmit power according toanother embodiment of the present invention.

It is proposed herein that subframe numbers are identical as m=n, andsubframes with the same subframe number are first subjected to transmitpower adjustment, and thereafter overlapping different subframes arereadjusted.

For UL signals transmitted to different cells, a tentative transmitpower is determined by respectively applying power limitation rules tooverlapping portions in the subframes having the same subframe number. Afinal transmit power is determined by applying the power limitation ruleto an overlapping portion in adjacent subframes.

FIG. 10 in (A) shows a case before adjusting a transmit power.

In FIG. 10 in (B), a transmit power of C2,m is determined to P2 byapplying the power limitation rule to C2,m and C1,n.

In FIG. 10 in (C), a transmit power of C1,n+1 is determined to P101 byapplying the power limitation rule to C2,m+1 and C1,n+1.

In FIG. 10 in (D), since C2,m and C1,n+1 overlap in consecutivesubframes, a transmit power of C2,m is finally determined to P3 byapplying the power limitation rule. Herein, the rule is applied underthe assumption that C1,n+1 is transmitted with P101.

FIG. 10 in (E) shows a finally determined transmit power.

It may be requested to guarantee a constant transmit power only for a ULsignal having a specific format during a specific time duration. Forexample, a PUCCH for carrying ACK/NACK or a PRACH may maintain atransmit power determined in initial transmission based on onetransmission unit, and thereafter a transmit power of UL signals toanother cell overlapping with a corresponding signal may be properlyadjusted or a change in a transmit power may be allowed within onetransmission unit. In addition, when a UL channel is modulated using ahigh-level modulation scheme (e.g., 16-QAM, 64-QAM, etc.), the constanttransmit power may be guaranteed as described above. If PUSCHtransmission using the higher-level modulation scheme overlaps withPUSCH transmission using a lower-level modulation scheme (e.g., BPSK orQPSK) in some subframes, a transmit power of PUSCH transmission usingthe lower-level modulation scheme may be adjusted in an overlappingportion or in the entirety of the subframe.

The aforementioned embodiments 7 to 10 may be combined. For example,since a PUCCH or a PRACH is a signal relatively important in comparisonwith other UL signals, a transmit power is determined only for oneoverlapping duration by applying the embodiment of FIG. 8, and then thedetermined transmit power is maintained. A PUSCH may be subjected topower adjustment by considering all durations overlapping with the PUSCHby applying the embodiments of FIG. 7, FIG. 9, and FIG. 10.

A priority used for assignment of a transmit power may be set for eachTA group. For example, a higher priority may be set to a TA group of aprimary cell in comparison with another TA group. As to cells belongingto a TA group having a low priority, a transmit power may bepreferentially reduced or transmission may be dropped. In addition, whena TA group index is assigned to a plurality of TA groups, a priority maybe put on a transmit power assignment in a low TA group index (or highTA group index) order, and a transmit power to a cell belonging to ahigh TA group index (or low TA group index) may be preferentiallyreduced. A lowest TA group index (e.g., 0) may be assigned to the TAgroup to which the primary cell belongs.

When a plurality of TA groups simultaneously transmit a plurality of ULsignals, if a total transmit power exceeds a maximum transmit power,some of the UL signals may not be transmitted throughrate-matching/puncturing. When a first UL signal transmitted in a firstTA group overlaps with a second UL signal transmitted in a second TAgroup, if a total transmit power in an overlapping portion exceeds amaximum transmit power, one of the first and second UL signals may notbe transmitted through rate-matching/puncturing in the overlappingportion.

In this case, which UL signal will be subjected torate-matching/puncturing may be determined in the following order. SomeOFDM symbols of PUSCH or PUCCH overlapping with SRS may be subjected torate-matching/puncturing. Some OFDM symbols of PUSCH overlapping withPUCCH may be subjected to rate-matching/puncturing. Some OFDM symbols ofPUSCH overlapping with PUSCH may be subjected torate-matching/puncturing.

When a first UL signal transmitted in a first subframe to a firstserving cell overlaps with a second UL signal(s) transmitted in twosubframes overlapping in the first subframe to a second serving cell, itcan be said that a transmit power of the UL signal is determined byusing a transmit power of the second UL signal(s).

The above embodiments are applicable to determine a transmit power ofSRS when a subframe boundary of another cell exists within an OFDMsymbol for transmitting the SRS in one cell.

As described above in the proposed embodiment, a method in which aplurality of TA groups are configured and a transmit power is adjusteddue to a misalignment of subframe timing among the TA groups may beapplied when a TA is misaligned among the plurality of TA groups by morethan a specific threshold. The threshold may be predetermined or may bedelivered by a BS to a UE.

Different methods may be applied to a case where the misalignment of thesubframe timing (or a duration in which transmission overlaps among aplurality of TA groups) is greater than or equal to the threshold and acase where it is less than or equal to the threshold. For example, ifthe subframe timing is misaligned by more than the threshold, some of ULsignals may be subjected to dropping/puncturing/rate-matching, and ifthe subframe timing is misaligned by less than the threshold, a transmitpower of some signals may be reduced. On the contrary, if the subframetiming is misaligned by less than the threshold, some of the UL signalsmay be subjected to dropping/puncturing/rate-matching, and if it ismisaligned by more than the threshold, a transmit power of some signalsmay be reduced.

If an overlapping duration is less than or equal to a specific length(e.g., one OFDM symbol), a transmit power of some channels or allchannels may be reduced only in the OFDM symbol or in the overlappingduration. Otherwise, a transmit power of some channels or all channelsmay be reduced in all transmission durations.

As to a PUSCH modulated using phase modulation such as BPSK/QPSK, atransmit power of an overlapping OFDM symbol in the above case may bereduced. As to a PUSCH modulated using QAM-type modulation such as16QAM, 64QAM, etc., transmission of the overlapping OFFDM symbol may bedropped by applying puncturing/rate-matching, etc. This is because, if atransmit power is reduced for a specific OFDM symbol, QAM demodulationcapability on the OFDM symbol may not be guaranteed.

FIG. 11 shows an example of TA adjustment for a TA group.

When a plurality of TA groups are configured, subframe timing for ULtransmission in a plurality of cells within each TA group is equallyapplied, whereas independent subframe timing may be applied for each TAgroup.

Subframe start timing (hereinafter, transmission timing) in one cell maybe adjusted by using a TA command or the like within a random accessresponse.

FIG. 12 shows overlapping caused by transmission timing adjustment.

If UL transmission signals overlap between consecutive subframes due totransmit timing adjustment with respect to the same cell, a portionoverlapping with a UL signal of a precedent subframe among UL signals(PUCCH, PUSCH, etc.) in a subsequent subframe may not be transmitted.This is because a start portion of a signal transmitted through asubframe includes a cyclic prefix (CP) of an OFDM symbol (or OFDMsymbol), and even if the CP is lost, may have a relatively less dataloss opportunity than other portions.

The present invention proposes that transmission timing is adjusted byapplying a TA command in cells belonging to the same TA groups, and if asubframe n overlaps with a subframe n+1 as a result, an overlappingportion (i.e., all or some of OFDM symbols) of the subframe n+1 and thesubframe n is not transmitted.

The subframe n and the subframe n+1 may belong to the same cell or maybelong to different cells belonging to the same TA group.

This is because a UE complexity may be significantly increased when a UEtransmits a radio signal by using the same RF module (i.e., power amp,etc.) with respect to cells belonging to the same TA group and the sameRF modules transmits a radio signal at different timings.

For example, if a TA command is received in a subframe n−6, theadjustment of UL transmission timing may be applied starting from asubframe n. If transmission of a UL signal (PUCCH/PUSCH/SRS, etc.) ofthe UE overlaps in a subframe n−1 and a subframe n due to the adjustmentof transmission timing with respect to serving cells belonging to thesame TA group, the UE may complete transmission in the subframe n−1 andmay not transmit an overlapping portion of the subframe n.

As to cells belonging to different TA groups, the UE may performtransmission directly even if transmission overlaps due to thetransmission timing adjustment based on the TA command. This is becausetransmission for different TA groups is performed independently bydifferent RF modules, and thus does not have a significant effect on aUE complexity even if signals are transmitted at different timings.

FIG. 13 shows UL transmission according to an embodiment of the presentinvention.

An end portion of a UL signal transmitted in a subframe n to a cell 1belonging to a first TA group (TAG1) overlaps with a start portion of aUL signal transmitted in a subframe n+1 to a cell 2 belonging to thefirst TAG1 due to timing adjustment depending on a TA command. A UE doesnot transmit an overlapping portion among UL channels transmitted to thecell 2.

A UL channel transmitted in a subframe n+1 of a cell 3 or cell 4belonging to a second TA group (TAG2) is transmitted irrespective oftiming adjustment of the first TAG1.

Whether transmission is performed in an overlapping portion in theconsecutive subframes may be reported by a BS to the UE.

FIG. 14 is a block diagram showing a wireless communication systemaccording to an embodiment of the present invention.

A BS 50 includes a processor 51, a memory 52, and a radio frequency (RF)unit 53. The memory 52 is coupled to the processor 51, and stores avariety of information for driving the processor 51. The RF unit 53 iscoupled to the processor 51, and transmits and/or receives a radiosignal. The processor 51 implements the proposed functions, procedures,and/or methods. In the aforementioned example, a serving cell and/or aTA group can be controlled/managed by the BS, and an operation of one ormore cells can be implemented by the processor 51.

A wireless device 60 includes a processor 61, a memory 62, and an RFunit 63. The memory 62 is coupled to the processor 61, and stores avariety of information for driving the processor 61. The RF unit 63 iscoupled to the processor 61, and transmits and/or receives a radiosignal. The processor 61 implements the proposed functions, procedures,and/or methods. In the aforementioned embodiment, an operation of the UEcan be implemented by the processor 61.

The processor may include Application-Specific Integrated Circuits(ASICs), other chipsets, logic circuits, and/or data processors Thememory may include Read-Only Memory (ROM), Random Access Memory (RAM),flash memory, memory cards, storage media and/or other storage devices.The RF unit may include a baseband circuit for processing a radiosignal. When the above-described embodiment is implemented in software,the above-described scheme may be implemented using a module (process orfunction) which performs the above function. The module may be stored inthe memory and executed by the processor. The memory may be disposed tothe processor internally or externally and connected to the processorusing a variety of well-known means.

In the above exemplary systems, although the methods have been describedon the basis of the flowcharts using a series of the steps or blocks,the present invention is not limited to the sequence of the steps, andsome of the steps may be performed at different sequences from theremaining steps or may be performed simultaneously with the remainingsteps. Furthermore, those skilled in the art will understand that thesteps shown in the flowcharts are not exclusive and may include othersteps or one or more steps of the flowcharts may be deleted withoutaffecting the scope of the present invention.

1-14. (canceled)
 15. A method for uplink transmission in a wirelesscommunication system, the method comprising: determining, by a userequipment (UE), a total transmission power including first and seconduplink signals; if the first uplink signal to be transmitted toward afirst cell belonging to a first timing advance group (TAG) at an n^(th)subframe overlaps the second uplink signal to be transmitted toward asecond cell belonging to a second TAG at an (n+l)^(st) subframe,determining, by the UE, whether to drop the first uplink signal at then^(th) subframe, where n is an integer≧1; and transmitting, by the UE,both the first and second uplink signals, or transmitting the seconduplink signal without the first uplink signal, according to whether thefirst uplink signal at the n^(th) subframe is dropped.
 16. The method ofclaim 15, wherein the first uplink signal to be transmitted toward thefirst cell includes at least one of a physical uplink control channel(PUCCH), a physical uplink shared channel (PUSCH) and a soundingreference signal (SRS), and wherein the second uplink signal to betransmitted toward the second cell includes at least one of a PUCCH, aPUSCH and an SRS.
 17. The method of claim 15, further comprising:determining, if the first uplink signal corresponds to a soundingreference signal (SRS) and the second uplink signal corresponds to aphysical uplink shared channel (PUSCH), that the SRS is dropped at then^(th) subframe.
 18. The method of claim 15, further comprising:applying a first timing advance to the first cell belonging the firstTAG to adjust uplink timing; and applying a second timing advance to thesecond cell belonging the second TAG.
 19. The method of claim 18,further comprising: receiving information about a first time alignmenttimer for the first TAG and information about a second time alignmenttimer for the second TAG; receiving a timing advance command for a firstgroup; and starting or restarting the first time alignment timer uponapplying the timing advance command.
 20. The method of claim 19, whereinthe timing advance command is received at an (n−6)^(th) subframe and thetiming advance command is applied at the n^(th) subframe.
 21. The methodof claim 15, wherein an overlapped portion between the first uplinksignal and the second uplink signal includes a part of an orthogonalfrequency division multiplexing (OFDM) symbol.
 22. A user equipment (UE)for uplink transmission in a wireless communication system, the UEcomprising: a radio frequency (RF) unit configured to transmit andreceive radio signals; and a processor operatively coupled with the RFunit and configured to: determine a total transmission power includingfirst and second uplink signals, and if the first uplink signal to betransmitted toward a first cell belonging to a first timing advancegroup (TAG) at an n^(th) subframe overlaps the second uplink signal tobe transmitted toward a second cell belonging to a second TAG at an(n+1)^(st) subframe, determine whether to drop the first uplink signalat the n^(th) subframe, where n is an integer≧1, wherein the RF unit isfurther configured to transmit both the first and second uplink signals,or transmit the second uplink signal without the first uplink signal,according to whether the first uplink signal at the n^(th) subframe isdropped.
 23. The UE of claim 22, wherein the first uplink signal to betransmitted toward the first cell includes at least one of a physicaluplink control channel (PUCCH), a physical uplink shared channel (PUSCH)and a sounding reference signal (SRS), and wherein the second uplinksignal to be transmitted toward the second cell includes at least one ofa PUCCH, a PUSCH and an SRS.
 24. The UE of claim 22, wherein theprocessor is further configured to determine, if the first uplink signalcorresponds to a sounding reference signal (SRS) and the second uplinksignal corresponds to a physical uplink shared channel (PUSCH), that theSRS is dropped at the n^(th) subframe.
 25. The UE of claim 22, whereinthe processor is further configured to: apply a first timing advance tothe first cell belonging the first TAG to adjust uplink timing; andapply a second timing advance to the second cell belonging the secondTAG.
 26. The UE of claim 25, wherein the processor is further configuredto: receive information about a first time alignment timer for the firstTAG and information about a second time alignment timer for the secondTAG; receive a timing advance command for a first group; and start orrestart the first time alignment timer upon applying the timing advancecommand.
 27. The UE of claim 26, wherein the timing advance command isreceived at an (n−6)^(th) subframe and the timing advance command isapplied at the n^(th) subframe.
 28. The UE of claim 22, wherein anoverlapped portion between the first uplink signal and the second uplinksignal includes a part of an orthogonal frequency division multiplexing(OFDM) symbol.